Radiotelegraphy



July 3, 1928. 1,675,987

A. H. MITTAG RADIOTELEGRAPHY Filed April 2, 1926 l Figl.

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Patented July 3, 1928.

UNITED STATES PATENT OFFICE.

ALBERT H. MITTAG, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

RADIOTELEGRAIHY.

Application filed .April 2, 1926. Serial N0. 99,364.

My invention relates to radiotelegraphy, 2 through a transformer 3.

and has for its principal object the provision of an improved system that is capable of accurately transmitting signals at a comparatively high rate of speed.

It is customary to supply energy to an antenna from a high frequency source and to control this energy by change in the saturation of a variable impedance device such as a magnetic amplifier which is connected to the antenna in series or parallel with the high frequency source and is provided with a saturation or exciting winding energized in accordance with'the signals to be transmitted. This method of controlling the energysupplied to the antenna involves the use of means for controlling the circuit of the saturation winding. Such circuit control means should be capable of clearly defining the periods of energization and deenergization of the exciting winding and should be capable of opening and closing at a high rate of speed in order to permit the rapid transmission of signals. Various circuit control means have been utilized in the past for controlling the saturation of the impedance device or magnetic amplifier but the operation of these control means has not been altogether satisfactory for the reason that they either do not operate with sufficient rapidity or are incapable of controlling currents large enough to saturate the magnetic amplifier. In accordance with my invention, the exciting current of the magnetic amplifier is supplied through an electron discharge or vapor electric device capable of carrying large currents and pro vided with a grid arranged to have its potential controlled in accordance with the signals to be transmitted. I

Myinvention will be better understood from the following description when considered in connection with the accompanying drawings and its scope will be pointed out in the appended claims.

Referring to the drawings, Fig. 1 is a dia grammatic showing of a transmitting system wherein my invention has been embodied. Fig. 2 shows a modified forinof magnetic amplifier. Fig. 3 shows'a modified arrangement for controlling the grid potential of the electron discharge device.

This system comprises aconsumption device, shown as an antenna 1, to which ourrent is supplied from'a high frequency source This current is controlled by magnetic amplifier units 4 and 5 which areconnected in parallel to the secondary terminals of the transformer 3 through a condenser 6 and are provided respectively with oppositely wound operating coils 7 and 8 and an exciting or saturation coil 9 and with oppositely wound opera-ting coils l0 and 11 and an exciting or saturation coil 12. With these connections, the magnitude of the current supplied to the antenna 1 is determined by the magnetic amplifier impedance which is controlled by the current transmitted through the saturation windings 9 and 12.

Current is supplied to the saturation coils 9 and 12 from a suitable source through supply lines 13, a switch 14, a smoothing reactor 15, resistors 16 and 17, and an electron discharge device 18. The device 18 is provided with anodes 19 and 19 connected to the opposite ends of the resistors 16 and 17, with a mercury cathode 20, with exciting electrodes 21 and 22 arranged to be connected to the cathode 20 through a source of exciting current shown as a generator 23, with a starting electrode 24 connected to the exciting electrode 22 through a resistor 25 and with grids 26 and 27 connected to the cathode 20 through resistors 28 and 29, resistors 30 and 31, and a bias battery 32. Assuming the switch 14 to be closed and the connections to be as heretofore described, no current is transmitted through the saturation coils 9 and 12 for the reason that the grids 26 and 27 are maintained at a negative potential by the battery 32.

A polarized quick acting relay 33 comprising a movable contact member'34, stationary contacts 35 and 36, operating coils 3'7 and 38, and a polarizing element 39 is provided for connecting the cathode 20 through a source 40 and a switch 41 either to the grid 26 through the resistor 28, or to the grid 27 through the resistor 30. Vhenthe contact 34 engages the contact 35, the grid 26 is charged to a positive potential by the source 40 and current from. supply means 13 is transmitted through the saturation coils 9 and 12. WVhen the contact 34 engages the contact 36, the grid 27 is charged to a positive potential by the source 40 and current is transmitted through the resistor 17. hen the contact 34 is in its illustrated position, both the grid 26 and the grid 27 are charged to a negative potential by the battery 32. A condenser 42'is provided for facilitating the transfer of the arc'between the anodes26 and 27.

The position of the movable contact mem-H ber 34 is controlled by the operating coil 38 which is arranged to be supplied with current from a source 43 through a resistor 44 and a switch 45 and the operatingcoil 37 which is arranged to be connected to a source 46 through a switch 47, a resistor 48 and a control deviceshown as a key 49; Assuming the switches 14, 41 45 and 47 to be closed and the control device to be in its open position, the movable contact 34 is maintained in engagement with the contact 35, current is transmitted. through the saturation coils 9 and 12, the impedance of the magnetic amplifiers is reduced to its minimum value and the antenna current is greatly reduced. Upon closure of the key 49, however, the-contact member 34 is moved into engagement with the contact 36, ourrentis transferred from the anode 26 to the anode 27, the inductance of the magnetic amplifiers is greatly increased and a corresponding increase in the antenna current is produced. In the operation of the apparatus, it has been found that the relay 33 operates very rapidly and that the current of the antenna can be changed in a manner to permit the sending of signals at a rate high "enough to permit the sending of approximately two hundred and fifty words per minute.

' Fig. 2 shows a modified form of magnetic amplifier wherein the saturation windings are omittediand the saturation current is supplied directly to the operating windings through a reactance winding 50. In this form of amplifier the left hand terminal of the resistor 16 is connected to the midpoint of the winding 50 and the junction between the windings 7 and 8 is connected 'to the anode 19. -The remaining connections are the same as those shown in Fig. 1.

Fig. 3 shows ,a modified arrangement for controlling the grid potentials of the electron discharge device 18. In this arrangement, potential is applied to the grids 26 and 27 through an impedance device shown as a resistor 51 which has its midpoint connected to the cathode 20 through the bias battery 32. Current for controlling the potential drop of the resistor 51 is supplied from a source 52 through a resistor 53 or from a source 54 through'the key 49.

Vtlhen the key 49 is in its illustrated open position, the potential of the grid '26 is negat ive,the potential of the grid 27 is positive,

thearc of the device 18 is between anode 19' and cathode 20, and the saturation of the magnetic amplifier is comparatively low. Upon closure of the key 49 however, the polarity oflthe potential applied. to the resistor 51 is reversed, and the arc of the device 18 is transferred from the anode 27 to the anode 26 thus increasing the saturation of the magnetic amplifier. i t r v, V j ,i

Theembodiments of the invention illustrated and described herein have been selected for the purpose of setting forth the principles involved. It will be apparent, however, that the invention is susceptible of being modified in many ways to meet the different conditions encountered in itsuse and I therefore aim to cover by the appended claims all modifications within the true spirit and scope of my invention.

lVhat I claim as new and desire to secure by Letters Patent of the United States, is:

1. The combination of an antenna, a source of high frequency current connected to said antenna, means connected to'said antenna for controlling the energy transmitted benected to said device,a magnetic amplifier provided with a windingconnected to said device, and means for controlling the impedance of said amplifier comprising an electron discharge device provided with a plurality of anodes one of which is connected to said winding and with means for causing cur rent to be transferred to and fro' between said anodes for controlling the current of said winding.

3. The combination of a consumptionde vice, a source of alternating current con nected to'sald device, a magnetic amplifier provided with an operating winding con nected to said device and with a saturation winding for controlling the impedance of said amplifier, an electron discharge device provided with a cathode, with a plurality of anodes one of which is connected to said saturation winding and with means comprising grids arranged tofcause current to be shifted to and'fro between said anodes, and means for biasing said grids to a negative potential. I

4. The combination of a-consumption device, a source of alternating current connected to said device, a magnetic amplifier provided; with an operating winding 'con: nected to said device in parallel with said source and with a saturation-winding for controlling the impedance of said amplifier, an electron discharge device provided with a cathode, with a plurality of anode-s one of which is connected to said saturation winding and with grids for controlling the current of said saturation winding, means loo ill)

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for biasing said grids to a negative potential, and means for alternatively changing the potentials of said grids to vary the current of said saturation winding.

5. The combination of a consumption device, a source of alternating current connected to said device, a magnetic amplifier provided with an operating winding connected to said device in parallel with said source and with a saturation winding for controlling the impedance of said amplifier, an electron discharge device provided with a cathode and an anode connected to said saturation winding and with a grid for controlling the current of said saturation winding, means connected to said grid through a plurality of resistors for biasing said grid to a negative potential, and means for charging said grid to a positive potential comprising a source of direct current, and means for connecting said direct current to said grid through only a part of said resistors.

6. The combination of a consumption device, a source of alternating current connected to said device, a magnetic amplifier provided with an operating winding connected to said device in parallel with said source and with a saturation winding for controlling the impedance of said amplifier, an electron discharge device provided with a cathode, with a plurality of anodes connected to said saturation winding and with grids for controlling the current of said saturation winding, means connected to said grids through a plurality of impedance devices for biasing said grids to a negative potential, means for charging said grids to a positive potential comprising a source of direct current, and a polarized relay for alternatively connecting said direct current source to said grids through only a part of said impedance devices.

7. The combination of a. consumption device, a source of alternating current connected to said device, a magnetic amplifier provided with an operating winding connected to said device in parallel with said source and with a saturation winding for controlling the impedance of said amplifier, an electron discharge device provided with a cathode and an anode connected to said saturation winding and with a grid for controlling the current of said saturation winding, means connected to said grid through a plurality of impedance devices for biasing said grid to a negative potential, means for charging said grid to a positive potential comprising a source of direct current, and a polarized relay for connecting said direct current source to said grid through only a part of said impedance devices.

8. The combination of a consumption device, a source of alternating current connected to said device, a magnetic amplifier pro vided with an operating winding connected to said device in parallel with said source and with a saturation winding, direct current supply means, and means for controlling the current of said saturation winding comprising an electron discharge device provided with a cathode and a plurality of anodes one of which is arranged to be connected to said cathode through a circuit including said current supply means and another of which is connected to said cathode through an impedance device, and means for transferring current from one of saic anodes to another to intermittently change the current of said saturation winding.

9. The combination of a consumption device, a source of alternating current con nected to said device, a magnetic amplifier provided with an operating winding connect ed to said device in parallel with said source and with a saturation winding, direct current supply means, and means for controlling the current of said saturation winding comprising an electron discharge device provided with a cathode and a plurality of anodes one of which is arranged to be connected to said cathode through a circuit including said current supply means and another of which is connected to said cathode through an impedance device, and means comprising grids interconnected with said cathode and interposed in the path of the anode currents for transferring current from one of said anodes to another to intermittently change the current of said saturation winding.

In witness whereof, I have hereunto set my hand this 1st day of April, 1926.

ALBERT H. MITTAG. 

